Abstract

Studied results of biostratigraphy and sedimentary petrology provide the geological information to clarify the stratigraphy and properties of sedimentary rocks in the eastern margin of the Cuu Long delta plain trough. On the basis of stratigraphic correlation of the wells and studying the structures of the area determine the survival, thickness of sediments and the ability to correlate with prospect objects on the southeastern shelf. The studied results have identified the basement rock of HG-1 and TC-1 wells which are Cretaceous metasandstone and are deposited in the freshwater fluvial with high energy conditions. The upper Paleogene sediments overlaied directly on the Cretaceous basement rock in TC-1 well but are completely absent in HG-1 well. The lithologic composition is main feldspathic litharenite sandstone which is formed in the freshwater fluvial and freshwater lacustrine. The result comparing the thickness of Paleogen sediments between the wells in studied area and the wells of Cuu Long basin show that they tend to be beveled toward the mainland and completely absent in the central area of ​​the Cuu Long delta plain trough. This can be hypothesized that during the early-middle Paleogene stage, the whole Cuu Long delta region and the southeastern continental margin were eroded or interrupted by the uplift of terrain, until late Paleogene the eastern margin was subsided gradually to open accumulation space for Oligocene and Neogene.